Molded electronic package, method of preparation and method of shielding-II

ABSTRACT

A packaged electronic circuit using molded plastics, Thick Film, and Polymer Thick Film technology, and achieving shielding of the circuitry and components of the package. In this invention at least one of electronic devices in the package is supported in a molded pocket in the molded substrate, and circuit traces are added to the surface of the substrate and the electronic device, simultaneously creating the circuit traces and making the interconnections with the components at the same time. Shielding, which is optional, can easily be printed over the planar surface of the circuit traces and components.

This application is a continuation of PCT/US98/27906, filed Jun. 30,2000.

TECHNICAL FIELD

This invention relates to the construction of a packaged electroniccircuit comprising a molded-plastic support base having a capacity toaccept and hold electronic devices or subassemblies thereof in a pocketwithin the molded substrate, and positioning them for interconnection(hereinafter referred to as “Molded Electronic Package”). The connectionto the electronic devices or subassemblies is intricately formed withthe placement of the circuit traces on the substrate. This is anadvantage over existing technology because it offers savings both incost and space. This is usually done at the surface level. The formationof the circuit traces by printing with Polymer Thick Film and theattachment to electronic devices is achieved by Polymer Thick Filmprinting technology and the substrate is formed with plastic moldingtechnology. The electronic devices may be semiconductors, integratedcircuits, electromechancial devices, other active components, passivecomponents such as Thick Film resistors or capacitors, or other devicesas defined later. While molded substrates are not new, and the use ofPolymer Thick Films technology and Thick Film Technology are not new,the combination of a molded substrate with a pocket built into themolded substrate and interconnecting the electronic devices in thepocket with Polymer Thick Film technology is new and fulfills along-felt need to be able to reserve the surface area above the tracearea for other circuits traces and electronic devices. Others have triedto accomplish this by other means of interconnecting by layering circuitboards as discussed below, but only with the advent of the new PolymerThick Films and the new molded plastic resins which have only recentlybecome available can we now accomplish the connecting of the electronicdevice in the pocket of the substrate material. The pocket permits theelectronic device to be supported by the substrate instead of beingsupported on the trace which allows for the use of the new Polymer ThickFilm technology to connect the electronic devices which previously didnot exist. This long felt need to further reduce the size of circuitboards for ever smaller products while containing or reducing costs ofthe resulting circuits has until now been unanswered by conventionalmethods.

BACKGROUND ART

A traditional printed circuit board comprises a supporting substrate andcopper-foil circuit traces. These traces are usually formed by thechemical etching of a pattern defined onto a laminated copper surface.Sometimes both front and back sides of the substrate carry circuittraces. Two-sided, or double-sided designs usually are interconnectedthrough vias (holes) that have copper deposited around the hole walls. Arelated technology exists known as Thick Film. Here the supportingsubstrate comprises flat, thin pieces of alumina (Al₂O₃) on which thetraces are printed with an ink containing metal, glass frit, and otheradditives. When fired at the correct temperatures the ink fuses to formconductive traces to which components can be soldered. An importantfeature to Thick Film technology is that conductive traces can beinterconnected by printed inks having specific electrical resistivityafter being heated in a kiln (firing).

A lessor-known technology exists known as “Polymer Thick Film” whereinconductive traces can be prepared on printed circuit board substrateusing polymer inks that contain polymer resins and metals, usuallysilver. Typically heat is used to cure or set the polymers in the inksto form reasonably stable circuit traces. In a manner similar to theThick Film process, carbon-filled inks can be used to interconnectcircuit traces with specific electrical resistances. Carbon prints,known as Polymer Thick Film resistors, can be printed onto traditionalcopper foil traces, or onto printed Polymer Thick Film conductivecircuit traces.

Countless variations of printed circuit boards exist, and manyvariations of the Polymer Thick Film process also exist. One applicationof both the printed circuit board process and the Polymer Thick Filmprocess is the Molded Circuit board. Here the process of converting alaminated sheet of material into the proper circuit board dimensions andhaving all the necessary holes, slots, and shapes are replaced bymolding these features into the board. Circuit traces are applied to aboard either during or after the molding process. One method for addingthe traces was to print them with conductive Polymer Thick Film inks.

In the past the molded board with Polymer Thick Film traces (baking ofthe Polymer Thick Film ink creates the conductive circuit traces) foundlimited acceptance for a number of reasons. Printed Polymer Thick Filmconductive traces have more resistance than copper foil traces. Also,electronic devices cannot be soldered to most Polymer Thick Film traces.Those electronic devices that were attached to solderable Polymer ThickFilm inks did not have good adhesion to the molded substrate after thesoldering process. Some Polymer Thick Film conductive inks contain leadwhich causes environmental concerns and which limits the ability torecycle the materials. Additionally, the molded plastic that couldwithstand soldering temperatures without warping were the engineeringgrade materials which are higher quality performing materials. These aremore expensive, however, and when used, the cost advantage of themolding process is often lost. Some simple applications of the MoldedBoard with Polymer Thick Film traces (but without pockets) designed tofit into a connector have been used commercially, but in generalcommercial production of this type product has been limited.

Printing conductive layers over circuit board traces that are connectedto and grounded by a ground plane is a known way to achieve shielding ofthe traces covered. The circuit traces are first sealed in an insulatinglayer, and then overprinted with a conductive layer. With thistraditional approach it is not possible to shield the components whichare attached to the circuit traces, but only the traces themselves.

Lassen's U.S. Pat. No. 4,602,318 describes achieving high densityelectronic networks by depositing filaments onto a substrate andencapsulating the filaments to achieve dimensional stability. Filamentsare conductive or made conductive by various means. Access to theseconductive traces is produced with the use of a high energy beam to cutthrough and expose the filaments. Lassen claims the use of epoxy resinsheets, and polyimide resin sheets to create his circuitry.

Parker's U.S. Pat. No. 4,912,844 describes using a heated punch todefine grooves and holes in a substrate. The grooves are then filledwith solder to create a circuit trace which connects electronic devices.Beaman's U.S. Pat. No. 5,371,654 describes a three dimensionalelectronic package with a plurality of assemblies interconnected byaligning the assemblies so they are adjacent, and interconnected by somemeans such as an elastomeric material, but other than a Polymer ThickFilm.

Capote's U.S. Pat. No. 5,376,403 describes ink formulations which can beused to form circuit traces, but Capote does not describe or claim usesfor his ink.

Hiller's U.S. Pat. No. 5,420,755 places a component in a hole cut intostandard circuit board material, but does not claim using molded pocketsin circuit boards. The component is attached with a standard solderconnection. Placement of the component is in a cut hole and the solderjoint is not different from using any common commercial solder joint toconnect the electronic devices.

McGinley's U.S. Pat. Nos. 5,599,595 and 5,688,146 describes how circuittraces can be added to molded plastic to achieve a printed connectorassembly. McGinley uses current technology to attach printed PolymerThick Film conductive traces to the top surface of the Polymer ThickFilm traces. McGinley uses current Polymer Thick Film methods to printresistors on the circuitry of the connector.

Marrocco's U.S. Pat. Nos. 5,646,231, 5,646,232, and 5,654,392 describethe use of rigid rod polymers to form a plastic molded circuit board. Nomention is made as to how this is done, nor are any claims madeconcerning molded pockets in the substrate or attachments of theelectrical devices placed in the pockets.

Nakagawa's U.S. Pat. No. 4,801,489 and Iwasa and Marooka's U.S. Pat.Nos. 5,066,692 and 4,970,354 describe how printed conductive inks can beused to create shielding properties on printed circuit boards, howeverall of these patents are for shielding on printed circuit boards. In myinvention there is no circuit board, but rather a molded substratecontaining inserted components. Also, In my invention the entire packagemay be shielded, and not just the circuit traces. This is a significantadvantage over printed shielding that shields only the traces.

Higgins' U.S. Pat. No. 5,639,989 describes how shielding of both circuittraces and components mounted on the substrate can be achieved. Higginspatent would require applying an insulating layer over both traces andcomponents and then applying a conductive layer over the insulatinglayer which connects to a ground plane. This is awkward to achieve sincethe surface is not planar, and these layers must be applied by spraying,dipping, pad printing, or some other method for applying a uniform thinlayer to an irregular surface. In my invention the circuitry andcomponents form a planar surface, and the layers can be easily printedwith screen printing or any other common commercial printing process.

DISCLOSURE OF INVENTION

The present invention provides a cost effective, highly functionalpackaged electronic circuit by combining the advantages of moldedsubstrates, Thick Film construction, and Polymer Thick Film technologyin a single package. The substrate may also be vacuum formed plastic,and shielding of both circuit traces and components contained in pocketsof the molded substrate may be achieved. All of these features areimportant developments that address the driving forces of the electronicpackaging industry, and that is to create smaller and less expensivepackaging alternatives. To do this I designed the molded support toaccept inserted electronic devices and connecting them with additivecircuitry which both adheres to the substrate and interconnects theindividual components. In FIG. 1 one variation of this concept is shown.The attached electronic devices may comprise a resistor, a capacitor, anLED, or it can comprise an electro-mechanical device such as a connectorpin or an off/on switch, or a bioelectrical functional component. Othersimple functional features may also be incorporated into the moldeddesign such as heat sinks, pins that connect front-side circuitry toback-side circuitry, or thermal vias (holes or openings in the board).The electronic device in the pocket may attach on a planar level of thesubstrate (horizontal plane, two dimensional), or the electronic devicein the pocket may attach either below or above the plane of the face ofthe molded substrate (three dimensional, vertical plane, in the z-axisof the substrate).

Subassemblies, which are smaller circuits complete with their ownelectronic devices and usually constructed on ceramic substrate, canalso be attached in the same manner as electronic devices. This couldinclude ceramic circuitry (complete with active and/or passivecomponents). It could also include ball-grid arrays or chip scalepackages. Multichip Modules can also be built up using moldedsubstrates, chips inserted into pockets, and the attachment techniquesdefined in this document.

The traditional circuit board package begins with a substrate whichsupports the circuit traces while in the Molded Electronic Package themolded substrate supports both the circuit traces and the electricaldevices, and the interconnection of the components is achieved byforming the circuit traces over both the electrical devices and thesubstrate. Connection can be directly to the electrical devices or canbe through vias (small openings or holes) in an insulating layer whichcovers the electrical devices. In the Molded Electronic Packageconnection can be directly by the trace or by a second material, such asa solder-paste or a conductive adhesive that is an extension of thetrace.

Benefits of this construction are as follows:

1) Since the electronic device is securely held in the pocket by themolded substrate, the electronic device need no longer rely on theadhesion of a Polymer Thick Film conductor ink to the substrate toremain secure in the circuit. Thus, this requirement of attachment orholding of the electronic device is no longer important in the selectionof a Polymer Thick Film conductor used to form the circuit traces.

2) Interconnection options are now available that do not require theextreme high temperatures of the soldering process. We therefore have abroader choice of molding material from which to prepare the moldedsubstrate making possible less expensive circuitry.

3) Because electronic devices, especially resistors, can be packaged inpockets in the board in the z-axis rather than mounted to the surface ofthe board, valuable space is now made available for the attachment ofother components. This is a very valuable feature when trying to designmore compact circuitry.

4) Because a wide range of materials are available for construction ofthe supporting molded plastic substrate, the design engineer can takeadvantage of different dielectric properties such as dielectricconstant, voltage breakdown resistance, and loss tangent. This onlybecomes possible because Molded Electronic Package packaging resolvesthe problems of heat sensitivity and adhesion properties as discussedabove.

5) Because electronic devices such as resistors can now be mounted underthe circuit traces in pockets in the molded plastic substrate ratherthan on top of the traces, one can now route traces to different partsof the circuit without resorting to multi layering the circuitry toavoid crossing the traces.

6) Resistor networks can now be designed below the circuit traces with ahigher packaging density than possible with resistors mounted on top oftraces, because the connection joint between the trace and theelectronic device is no longer also serving as the physical support forthe electronic device, and it can therefore be a smaller, more finitejoint.

7) Choices of polymer resins are available for the supporting substrate,one being Polyimide, the prefered embodiment, and also are polymers andcopolymers of Epoxies, Phenolics, thermoset Polyesters, SyndotacticPolystyrene, Polyethylene Terephthalate, Polybutylene Terephthalate,Polyphenylene Sulfide, Polyamide, Liquid Crystal Polymers, PolyphenyleneOxide, Polycyclo Terethalate and rigid rod polyphenylene. With the broadchoice of polymer resins it is now possible and practical to design,build and use circuitry that can be recycled.

8) The preparation of Molded Electronic Package circuitry can beachieved without costly, environmental risky processes, such as the useof lead solders and acids for etching, which are necessary in thecurrent printed circuit board industry.

9) The capitalization required to set up this Molded Electronic Packageprocess is much less than for other printed circuit board factories.

10) Since molded substrates have their physical dimensions defined inthe molding process they can be easily stacked in magazines for printingand baking on automated equipment. It is not practical to processtraditional circuit board substrates in this way because they must behandled in large sheets to achieve economical conversion to the finalsize and shape. The adaptability of the Molded Electronic Package toautomated handling means its user could set up manufacturing in thecountry of choice instead of in cheap labor markets as is common in theprinted circuit board industry today.

11) Silicon chips can be placed into pockets and attached directly tothe Molded Electronic Package board without mounting them first in oneof the many carrier alternatives currently used. This not only reducescost and saves space, but allows easy rework of faulty chips by simplyremoving the faulty chip from the pocket, inserting a new one, andrepeating the printing process which attaches the chip.

12) Since resistors, sub assemblies, and other components can be locatedin the board and under the circuit traces rather than on the board andover the circuit traces, it is now possible to use an economical printprocess to seal both the circuitry and the components in dielectric, andoverprint the package with a Polymer Thick Film conductive shieldinglayer.

13) Extremely low cost circuitry can be prepared from vacuum formedplastic. In this process inexpensive sheets of plastic are formed threedimensionally under heat and vacuum pressure. This inexpensive processcan be used to form the pockets for inserting components, and otherdimensional requirements at the same time.

BRIEF DESCRIPTION OF DRAWINGS

These and other objects, features and advantages of the presentinvention will become apparent upon further consideration of thefollowing detailed description of the invention when read in conjunctionwith the figures, in which:

FIG. 1 is a side view of an electronic device inserted into a moldedpocket and connected by a printed Polymer Thick Film conductive ink. Theassembly is sealed in a solder mask.

FIG. 2 is a side view of an electronic device inserted into a moldedpocket and connected by a printed Polymer Thick Film ink that acceptscopper plating to become conductive. The electronic device also acceptsplating as the means of attachment to the circuit. The assembly issealed in a solder mask.

FIG. 3 is a side view of an electronic device inserted into a moldedpocket and connected by a printed Polymer Thick Film ink that is bothconductive in itself and accepts copper plating to enhance itsconductivity and/or solderability. The electronic device does not acceptthe copper plating, but is connected by the adhesion of the printedPolymer Thick Film conductive ink. The assembly is sealed in soldermask.

FIG. 4 is a side view of an electronic device inserted into a moldedpocket and connected to a printed Polymer Thick Film ink that acceptscopper plating to become conductive and solderable. The electronicdevice connection is made by a solder joint. The assembly is sealed in asolder mask.

FIG. 5 is a side view of an electronic device inserted into a moldedpocket and sealed by a printed solder mask. Openings in the solder mask(also known as vias) provide the site through which the printed PolymerThick Film ink is connected to the electronic device.

FIG. 6 is a side view of an electronic device inserted into a moldedpocket and connected by a printed Polymer Thick Film ink that acceptscopper plating to become conductive. The electronic device is sealed onits top surface by a printed solder mask, and the connection to theelectronic device is made through molded vias from the reverse side ofthe board. In this case a conductive adhesive makes the connectionbetween the conductive trace and the terminal sites of the electronicdevice.

FIG. 7 is a side view of two electronic devices inserted into twodifferent molded pockets in the substrate. One electronic device setsslightly above and the other slightly below the horizontal plane of thesubstrate. Both are connected with the printing of the Polymer ThickFilm conductor used to form the conductive traces of the circuit.

FIG. 8 is a side view of a subassembly inserted into a molded pocket ofthe substrate. This subassembly consists of several layers of circuitryand could have other electrical devices incorporated into its design.The entire subassembly is connected by the Polymer Thick Film conductivetraces which are printed onto the substrate and the subassembly. Theconductive material also connects the different layers of thesubassembly, however, this interconnection could be intricate within thesubassembly with the Polymer Thick Film connection only made to the topsurface of the subassembly.

FIGS. 1 through 8 show the use of a solder mask to seal portions of theassembly. The solder mask is performing as an insulating protectivelayer. Other printed polymer dielectrics exist for this purpose that arenot solder masks. Dielectrics can offer specific electrical propertiessuch as dielectric constant, loss tangent, and voltage breakdownproperties which can be important in the design of a circuit.

BEST MODE FOR CARRYING OUT THE INVENTION

The novel combination of Thick Film, Polymer Thick Film, and plasticmolding technology forms the basis of the cost savings and designadvantages of this invention. The specific role of the molded substrateis to give form and support for the electric package. If the dielectricproperties of the substrate become part of the function of the circuit,the role of the molded plastic is to optimize performance by providingthe correct dielectric properties. In all cases the substrate provideselectrical insulation between circuit traces. The role of the Thick Filmis to provide passive functions, such as resistance or capacitance,within the electrical circuit. Thick Film constructions can also providesubassemblies containing active electronic devices and functions, suchas transistors, diodes, integrated circuits, and other similar devicesused in the packaging of electronic circuits. The function of PolymerThick Film in this combination is to provide the interconnecting tracesof the circuit. This fills the role served by the etched copper tracesof a traditional printed circuit board. The Polymer Thick Film circuittraces are deposited normally by printing. The materials that can beused for printing circuit traces include inks filled with conductivefillers, such as silver, copper, silver plated copper, carbon, and couldinclude any other filler that produces a suitable electrical conductivecurrent path. The Polymer Thick Film conductor can also be a nonconductive material which, when printed, provides a sensitized tracewhich accepts metal plating, and in this way produces an electricallyconductive path. The metal deposited in the plating process will providethe conductivity while the printing material only defines the image toselectively accept metal plating.

Polymer Thick Film materials can also provide other functions within thecircuitry, such as resistance, capacitance, and dielectric separationbetween layers of a multilayer construction. These functions can be partof the total construction, but are not novel to this invention. It isthe interconnection of the electronic devices that are held within themolded frame that is an improvement over existing technology.

Polymer Thick Film materials can be used to print solid layers ofconductive material over a circuit which is insulated with a insulatingdielectric material. When a solid layer is required on one surface of acircuit, known as a ground plane, this also can be printed with PolymerThick Film materials.

Because the circuitry and the components are constructed to have acommon planar surface it is now possible to seal this surface with ainsulating layer, or dielectric layer, and then cover the entire surface(or any portion thereof) with a conductive layer that is grounded. Inthis way shielding of the circuit is complete. Both components andcircuit traces are enclosed in the same shielding envelope. This is noteconomically possible when the components are soldered to the surface ofa printed circuit board, or attached with wire leads. Shielding ofelectronic packages is becoming more and more important, and thistechnology is best suited for being prepared with an inexpensive printedor plated conductive layer.

Throughout this description electronic device is defined as a passivecomponent which serves a function within the circuit such as a resistoror capacitor, or an active component such as a transistor or a diode oran integrated circuit, or a semiconductor, or a multichip Module, or asilicon chip. An electronic device can also be a plastic ball grid arrayor a chip scale package, or a subassembly of circuitry and components.An electronic device can also be an electro-mechanical device such as aconnector pin or an off/on switch, or a bioelectrical component.

Throughout this description Thick Film is defined as that process forpreparing electronics circuitry that uses ceramic materials in the inkformulations in contrast to Polymer Thick Film where the ink formulasare based on polymer materials.

Throughout this description a molded substrate is defined as a supportfor an electronic circuit molded from any available plastic resinsuitable for the purpose such as Polyether Imide which is preferred forits combination of low cost, ability to withstand high temperatureexposures as experienced in a commercial soldering process, ability tomold flat, remain flat throughout subsequent processing, and itsformation of strong adhesive bonding with most Polymer Thick Film inks.Other plastics that can be used to construct molded substrates include,but are not limited to Epoxies, Phenolics, thermoset Polyesters,Polyethylene Terephthlate, Polybutylene Terephahlate, PolyphenlyeneSulfide, Polyamide polymers and copolymers, Liquid Crystal Polymers,Polyphenlyene Oxide, Polycyclo Terethalate, Syndotactic Polystyrene, andrigid rod Polyphenylenes. In the examples given in this description aspecific size is given for the pocket and the electronic device insertedinto the pocket. This is a practical and convenient size, both for anexample and for actual assembly, however the specific size is given forexample only, and an infinite number of sizes could be used.

Throughout this description a Polymer Thick Film conductor ink isdefined as any ink, screen printed, pad printed, or printed with anyother commercial process which deposits material that upon processingwill conduct electricity with a resistivity low enough for the print toserve as a conductive trace in an electronic circuit. This is normallyless than one tenth of an ohm per square in sheet resistance as printed.Examples of Polymer Thick Film conductor inks are Asahi LS 504J Silver,Asahi LS 506J Silver, Asahi Copper CU-051, and Grace 4001 Silver.

Throughout this description a fusible Polymer Thick Film conductive inkis defined as an ink which contains metal fillers which upon processingmelt and solidify in a manner similar to solder reflowing, and whichupon processing form an adhesive bond to the supporting substrate. Suchinks usually have low resistivity and are capable of accepting solder toform a solder joint between a conductive trace and a electronic device.Examples of fusible conductor inks are SVT EU 1328, Kester Ormet 1200,and Kester Ormet 2005.

Throughout this description a conductive adhesive is defined as a blendof polymers and conductive fillers such as metals which when appliedjoins a circuit trace and a electronic device and upon processing formsa conductive joint.

FIG. 1 shows the molded substrate 1 holding an electronic device 2. Thetraces are connected in the circuit by a printed Polymer Thick Filmmaterial 3 such as Asahi LS 504 J Silver ink that produces bothconductivity for the circuit traces and connection to the component. Thesubstrate is shown as planar (flat), but may also be non-planar (notflat-three dimensional). A solder mask layer 4 seals the package. Theadvantage to this process is that the silver ink is easy to use and hasfewer processing steps. The disadvantage is that silver inks have moreresistance than copper foil, and they normally do not accept solder asmay be required in some other assembly process. The point of attachment5 between the conductive trace and the electronic device is where theconductive ink falls directly onto the electronic device. The ink formsan adhesive bond to the component making the electrical connection. Theink can also be a fusible Polymer Thick Film conductive ink such as SVTEU 1328 which accepts solder attachment and therefore has an advantageover conventional silver inks.

FIG. 2 shows a variation of this concept where the molded substrate 1holds an electronic device 2. The traces may be connected in the circuitby a printed Polymer Thick Film material 6 that has been plated withcopper 7 to produce both conductivity and electrical connection to theelectronic component. A solder mask 4 layer has sealed the package.Notice that no solder is needed to connect the traces to the electronicdevice. The plating process provides both a conductive path andconnection, or the point of attachment 5, to the electronic device. ThePolymer Thick Film conductive trace can be a non-conductive sensitizingink such as Asahi ACP 007-2P, or it can be a conductive inks such asAsahi Cu 051 Copper ink, Asahi LS 504 J Silver ink, Asahi 30 SK Carbonink, or any ink by any manufacturer that functions in a manner similarto those mentioned. This approaches the conductivity of copper foil. Adisadvantage of the Asahi ACP 007-2P is an additional processing step toplate the copper onto the printed Polymer Thick Film ink.

FIG. 3 shows a variation of the concept in FIG. 2 where the copperplating 7 does not occur directly onto the component 2. Here theprincipal carrier of the current is the copper plating 7 which is platedonto the Polymer Thick Film ink 6, however here the Polymer Thick Filmink serves a dual role. It sensitizes the image to be plated, and itforms an electrical conductive bond to the electronic device in a mannersimilar to a conductive adhesive. The point of attachment, 5, is betweenthe Polymer Thick Film ink 6 just as in FIG. 1.

FIG. 4 shows a variation of this concept in FIG. 2 where the copperplating 7 on the conductive ink 6 does not connect to the component 2held by the molded substrate 1, but only brings the trace adjacent tothe electronic device. A second material 8 is then used to make theconnection from the trace to the component. This second material can bea solder material, such as Multicore's WS 12AAS88, a conductive adhesivesuch as Multicore's M-4030 Ag/TP, or a fusible Polymer Thick Film inksuch as Summit Valley Technologies EU 1328, or any material by anymanufacturer that performs in a manner similar to those mentioned. Theadvantage of this variation is a broader choice of electronic devicesthat can be connected in this manner, and the ability to design aproduct to meet specific performance requirements such as flexibility ofthe substrate base, heat stability, or the reduction in lead content.The circuit is protected by a solder mask or dielectric layer 4. Thepoint of attachment 5 is then a combination of the bonding between thecopper plating 7 and the solder (or conductive adhesive) 8 which bondsto both the copper plating 7 and the component 2.

FIG. 5 shows another variation of this concept where a Polymerdielectric layer such as a solder mask 4 covers the molded substrate 1so that the surface chemistry of the surface to which the polymerconductive trace 3 must bond is enhanced. The layer can either coveronly the molded surface or it may cover both the molded plastic and aportion of the electronic device. If the electronic device 2 is covered,attachment to the electronic device is through vias in the dielectriclayer 4 of the circuit. A fusible Polymer Thick Film conductive ink suchas SVT EU1328 is used and a surface mount electronic device 9 is placedonto the ink traces while the ink is still wet. The assembly isprocessed in a hot vapor reflow oven at 215° C. for two minutes whichattaches a surface mount electronic device and forms the point ofattachment 5 for the inserted electronic device.

FIG. 6 shows another variation of this concept, but here the traceprinted is a non conductive Polymer Thick Film ink 6 which is copperplated 7 and connected to the electronic device 2 through molded vias inthe reverse side of the substrate 1 while the pocket remains on theother side. Preferably the connection is made with a conductive adhesive8. This point of attachment 5 can also be made with a fusible polymerThick Film ink such as SVT EU1328, any suitable commercial solder pastesuch as Multicore's WS12AAS88, or the natural conductivity of a silverPolymer Thick Film conductive ink such as Asahi LS 504J. The advantageof this design is to free the top surface of the package forconstruction of other circuit functions.

FIG. 7 shows the molded substrate 1 holding two electronic devices 2 and10 such as Thick Film resistor networks or some other electronicdevices. The traces are printed to form a circuit using a Polymer ThickFilm material such as Asahi LS 504J Silver ink or SVT EU 1328 fusibleconductive ink that produces both conductivity for the circuit tracesand connection to the electronic devices. One electronic device 10 isslightly raised above the surface of the substrate 1 and the seconddevice 2 is slightly lower that the surface of the substrate 1. Thepoint of attachment 5 between the conductive Polymer Thick Film ink 3and the electronic device is where the conductive Polymer Thick Film inkfalls directly onto the electronic devices 2 and 10. The ink bonds tothe electronic devices making an electrical connection. Even thoughdevices 2 and 9 are not flat with the substrate 1, attachment is stillpossible and situations may arise where this condition may even bepreferable.

FIG. 8 shows the molded substrate 1 holding a multilayer subassembly 11in the pocket of the substrate 1. The traces are printed to form acircuit using a Polymer Thick Film material 3 such as Asahi LS 504JSilver ink or SVT EU 1328 fusible conductive ink that produces bothconductivity for the circuit traces and connection 5 to the multilayersubassembly 11. The point of attachment 5 between the conductive traceand the subassembly is where the conductive ink 3 falls directly ontothe multilayer subassembly. All layers of the multilayer can be attachedat this point, or they can be independently connected within its ownstructure. The ability to place more than one electrical device ormultilayer subassemblies which can have layers of circuitry on eachsurface used to construct the multilayer expands greatly thefunctionality of the package.

Another variation of this invention is that of an active electronicdevice, such as a silicon chip, integrated circuit, or semiconductor,can be connected in the circuit in any of the processes shown in FIGS.1-8.

Another variation of this invention is using a subassembly, such asceramic circuit to which other components are, or can be, attached.

Another variation of this invention is when the electronic devices madeon separate plastic moldings are inserted into the Molded ElectronicPackage in place of the Thick Film components or sub assemblies.

Another variation of this invention is when electronic devices made onprinted circuit board materials such as FR4, FR2, CEM1, CEM3, andpolyimide laminate are inserted into the Molded Electronic Package inplace of the Thick Film electronic devices or sub assemblies.

Another variation of this invention is when a dielectric material isused to seal the entire package, or a portion thereof, and a PolymerThick Film conductive material is used to shield the circuit traces andthe inserted components.

EXAMPLE 1

A substrate is molded of a preferred material commonly called PolyetherImide, but may be molded from such materials as but not limited toPolyethylene Terephthalate, Polybutylene Terephthalate, PolyphenyleneSulfide, Polyamide, Liquid Crystal Polymers, Polyphenylene Oxide,Polycyclo Terethalate, thermoset Epoxies, thermoset polyester, thermosetPhenolic, syndotactic polystyrene or a rigid rod polyphenylenes. Themolded substrate contains a pocket 0.5 cm by 1.25 cm and 0.25 cm deep. Aceramic substrate of the same or slightly smaller dimensions on which isprinted a resistor array is placed in this pocket. Circuit traces areprinted on the molded substrate with a Polymer Thick Film conductive inksuch as Asahi LS 504 J and cured at 140° C. in a box oven for 30 minutesor on a conveyorized infrared belt furnace at a setting to give the samedegree of cure. The circuit traces terminate directly on the terminalsites of the electronic device, and in this way attachment is achieved.This attachment is simultaneous with the formation of the circuit on thesubstrate.

EXAMPLE 2

A substrate is molded of a suitable material such as described inExample 1 and fitted with an electronic device inserted into a moldedpocket as described in Example 1. Circuit traces are printed on themolded substrate with a Polymer Thick Film conductive ink such as AsahiACP-007-2P Copper paste and cured at 150° C. for 30 minutes in a boxoven or on a conveyorized infra red belt furnace at a setting to producethe same degree of cure. The circuit traces terminate directly on theterminal sites of the electronic device. The assembly is placed in anelectroless copper bath such as Enthone CU-705. As copper plated on theelectronic device and the Polymer Thick Film traces the circuit becomeelectrically conductive, and at the same time attachment of theelectronic device is achieved.

EXAMPLE 3

A substrate is molded of a material such as described in Example 1 andfitted with an electronic device inserted into a molded pocket asdescribed in Example 1. Circuit traces are printed on the substrate witha Polymer Thick Film conductive ink such as Asahi ACP-051 Copper pasteand cured at 150 degrees C. for 30 minutes in a box oven, or on aconveyorized infra red belt furnace at a setting to produce the samedegree of cure. The circuit traces terminate directly on the terminalsites of the electronic device, and in this way attachment of theelectronic device is achieved. This attachment is simultaneous with theformation of the circuit on the substrate. The circuit is naturallysolderable and other electronic devices can be attached by soldering.The circuit can also be copper plated as in Example 2 to enhanceconductivity, solderability, and or the quality of the attachment to theelectronic device in the pocket.

EXAMPLE 4

A substrate is molded of a material such as described in Example 1 andfitted with an electronic device in the molded pocket as in Example 1.Circuit traces are printed on the molded substrate with a Polymer ThickFilm conductive ink such as Asahi ACP-007-2P Copper paste and cured at150 degrees C. for 30 minutes in a box oven, or on a conveyorized infrared belt furnace at a setting to produce the same degree of cure. Thecircuit traces terminate next to but not directly on the terminal sitesof the electronic device. The assembly is placed in an electrolesscopper bath such as Enthone CU-705. As copper plates onto the PolymerThick Film traces the circuit become electrically conductive. Attachmentof the electronic device is achieved by applying and reflowing a solderpaste such as Multicore WS 12AAS88.

EXAMPLE 5

An alternative to Example 4 is to make the attachment with a conductiveadhesive such as Multicore M-4030 Ag/TP or an fusible ink such as SVT EU1328. The process for curing the conductive adhesive is to apply thematerial and bake it in a box oven for 30 minutes at 140 degrees C. Theprocess for reflowing the fusible ink consists of heating in a Hot VaporReflow process for 2 minutes at 215° C., or heating the ink in aconveyorized infra red oven, or any commercially available heat transferprocess available for melting (reflowing) solder.

EXAMPLE 6

A substrate is molded of a material such as described in Example 1, andfitted with an electronic device in a molded packet as described inExample 1. The assembly is overprinted with a dielectric such as AsahiCR-20G ink which has vias to expose the termination site of the insertedcomponent. Circuit traces are printed on the molded substrate with aPolymer Thick Film conductive ink such as SVT EU 1328. A surface mountcomponent such as a resistor is also placed onto the circuit while theink is still wet. The assembly is dried at 120° C. for 5 minutes andthen reflowed in a hot vapor furnace at 215° C. for 5 minutes. Thecircuit traces terminate directly on the terminal sites of theelectronic devices, and in this way attachment is achieved upon reflowof the ink. This attachment is simultaneous with the formation of thecircuit on the substrate.

EXAMPLE 7

A substrate is molded of a material such as described in Example 1, andfitted with an electronic device inserted into a molded pocket asdescribed in Example 1. The entire surface of the assembly is sealedwith a dielectric print using Asahi CR-20G dielectric ink. circuittraces are printed on the reverse, or back side of the board using AsahiACP-007-2P copper ink which is cured at 150° C. for 30 minutes in a boxoven or on a conveyorized infra red belt furnace at a setting to producethe same degree of cure. The assembly is placed in an electroless copperbath such as Enthone CU-705 for the proper amount of time to achieve anelectroless deposition of copper on the printed traces. This usuallyrequires about 30 to 45 minutes. Vias have been molded in the substrateto give access to the termination site of the component from thereverse, or back side of the substrate. A conductive adhesive such asMulticore's M-4030 Ag/TP is deposited to achieve an electricalconnection between the conductive traces and the termination sites ofthe electronic device which are exposed by the vias in the moldedsubstrate.

EXAMPLE 8

In examples 1-7 the components have termination sites to whichattachments are made, but they do not have leads (metal wires or flatmetal extensions from the termination sites). Any of the electronicdevices in examples 1-7 that can be acquired as leaded components areassembled in this example by mounting them in molded pockets thatsupport the device and its leads so that one is able to interconnect theleads of the device using the Polymer Thick Film materials andprocessing described in examples 1-7.

EXAMPLE 9

A substrate is molded of a material such as described in Example 1 andfitted with a chip. Circuit traces are printed with Polymer Thick Filmthat connect to the chip as in Examples 1 through 7 to form a smartcard.

Industrial Applicability

While the present invention has been described with respect to preferredembodiments, numerous modifications, changes, and improvements willoccur to one skilled in the art without departing from the spirit andscope of the invention.

The electronic packaging industry has a concern when ceramic componentsare attached to circuit board materials made of polymers because thethermal coefficient of expansion of the polymers and the ceramic are sodifferent that stresses occur in interconnection joints due totemperature changes. For this reason surface mounted ceramic devices arenormally less that 10 millimeters. However our laboratory tests haveproved that a ceramic inserted component or subassembly held in aPolyimide molded pocket that is 12.5 millimeters by 25 millimeters, andsecured by a thermal setting adhesive, will withstand repeated thermalcycling without cracking, delaminating, losing continuity, or changingin resistance. These test were from approximately −40° C. to a maximumtemperature that was increased as the number of cycles progressed. Themaximum temperature started at 80° C.; the test was terminated with nofailures of the test patterns when the maximum temperature reached 180°C. These test provide evidence that the inserted component asconstructed in the description of this patent is more reliable thantraditional surface mount devices.

Another concern of one skilled in the art is whether printed tracescould be prepared reliably as the traces must pass over a parting linewhere the ceramic insert and the polymer pocket meet. Our lab testsdemonstrate it is difficult to print across the gap that exists if thegap is more than about 0.02 to 0.04 millimeters. Laboratory testing todate show that filling that gap with polymer materials is important toproviding the necessary print surface for a sharp circuit trace image,and giving the trace the durability to pass the different stress forcessuch an interconnection joint might be expected to encounter. Our testsindicate that a gap >0.02 mm and <0.04 mm needs to be filled withdielectric filling material. In our lab tests we have used thermosetmaterials, but results indicate in certain cases materials similar to aliquid photoimagable solder mask would be preferred. Liquidphotoimagable material can be applied in such a way that it levels byreason of gravity forces and natural surface tension. This allows forthe filling of the gap and making the gap level with the rest of theplanar surface. Photoimaging of the vias through which printedinterconnections is made is accurately done with this process, and thisis important when making small constructions with narrow, tighttolerance prints.

To date I have found that ceramic inserts in the range of 0.5millimeters thickness is preferred for insert components. This is about⅓ the thickness of traditional circuit board materials, and therefore apocket will be supported by plastic roughly twice the thickness of theceramic. It may be possible, however, that thinner ceramic will haveadvantages, especially when the plastic substrate thickness is alsothinner.

What is claimed is:
 1. An electronic package structure comprising: amolded substrate having first and second opposing surfaces, and anelectronic device disposed on one of the said surfaces: said moldedsubstrate having a molded pocket on one of said opposing surfaces intowhich said electronic device is supported in said pocket; wherein saidelectronic device is connected via Polymer Thick Film printed on thesurface of said molded substrate and exposed surface of the electronicdevice contained in the molded pocket.
 2. The structure of claim 1,wherein said printed surface of said molded substrate and terminal sitesof said exposed surface of the electronic device contained in the moldedpocket lie substantially in a plane.
 3. A structure as defined by claim1, wherein said printed surface of said molded substrate and terminalsites of the exposed surface of the electronic device contained in themolded pocket are in a non-planer configuration to each other.
 4. Thestructure of claim 1, wherein contact surfaces of said electronic deviceare sealed with a printed insulating layer leaving a via through which adevice is attached to the trace with Polymer Thick Film ink.
 5. Thestructure of claim 1, wherein said electronic device is a passivecomponent.
 6. The structure of claim 1, wherein said electronic deviceis an active component.
 7. The structure of claim 1, wherein saidelectronic device is an electromechanical device.
 8. The structure ofclaim 1, wherein said electronic device is an connector pin.
 9. Thestructure of claim 1, wherein said electronic device is an bioelectricalfunctional component.
 10. The structure of claim 1, wherein saidelectronic device is a Thick Film construction.
 11. The structure ofclaim 1, wherein said electronic device is a Polymer Thick Filmconstruction.
 12. The structure of claim 1, wherein said electronicdevice is ball-grid array.
 13. The structure of claim 1, wherein saidelectronic device is a chip scale package.
 14. The structure of claim 1,wherein said electronic device is a Multichip Module.
 15. The structureof claim 1, wherein said electronic device is an integrated circuit. 16.The structure of claim 1, wherein said electronic device is asemiconductor.
 17. The structure of claim 1, wherein said electronicdevice is a subassembly.
 18. An electronic package structure comprising:a molded substrate having first and second opposing surfaces, and anelectronic device disposed on one of the said surfaces: said moldedsubstrate having a molded pocket on one of said opposing surfaces intowhich said electronic device is supported in said pocket; and PolymerThick Film inks are used to print the circuitry on the substrate, butnot connect to the said electronic device; and A second Polymer ThickInk is used to connect the first Polymer Thick Film circuit and theexposed surface of said electronic device contained in the moldedpocket.
 19. The structure of claim 1, wherein the connection is made totermination sites of an electronic device with a non-conductive PolymerThick Film ink and both the ink and the termination sites subsequentlyaccepts copper plating to become conductive and simultaneouslyconnected.
 20. The structure of claim 1, wherein the terminal sites ofthe said electronic device does not accept copper plating but isconnected by the adhesion of the printed conductive Polymer Thick Filmink and whereby the Polymer Thick Film ink is both conductive in itselfand accepts copper plating to enhance its conductivity or solderability.21. The structure of claim 1, wherein said electronic device connectedto a Polymer Thick Film ink that accepts copper plating to becomeconductive and solderable, and wherein the electronic connection to theelectronic device is enhanced with a solder joint.
 22. The structure ofclaim 18 where the solder replaces the second conductive Polymer ThickFilm ink.
 23. The structure of claim 1, wherein said electronic deviceand substrate is sealed with a dielectric insulating print, and openingsor vias in the dielectric print provide the site through which theprinted conductive Polymer Thick Film ink is connected to the electronicdevice.
 24. An electronic package structure comprising: a moldedsubstrate having first and second opposing surfaces, and an electronicdevice positioned in one of the said surfaces: and said molded substratehaving a molded pocket on one of said opposing surfaces into which saidelectronic device is supported; and Polymer Thick Film traces areprinted on opposing surface of said molded pocket, and said pocket hasvias that open to the opposing surface of said substrate; andtermination sites of said electronic device are aligned with the vias insaid pocket; and wherein said electronic device is connected throughsaid molded vias from the opposing surface to the bottom of the pocketof the substrate; and a conductive adhesive makes the connection betweenthe conductive traces on the opposing surface of the substrate and theterminal sites of the electronic device.
 25. The structure of claim 1,wherein a plurality of electronic devices are placed in one or morepockets in the molded substrate and interconnected by printing of theconductive Polymer Thick Film inks used to form the conductive traces ofthe circuit.
 26. The structure of claim 1, wherein the molded substrateis molded from resin of Polyether Imide.
 27. The structure of claim 1,wherein the molded substrate is molded from resin of PolyethyleneTerephthalate.
 28. The structure of claim 1, wherein the moldedsubstrate is molded from resin of Polybutylene Terephthalate.
 29. Thestructure of claim 1, wherein the molded substrate is molded from resinof Polyphenylene Sulfide.
 30. The structure of claim 1, wherein themolded substrate is molded from resin of Polyamide.
 31. The structure ofclaim 1, wherein the molded substrate is molded from resin of LiquidCrystal Polymers.
 32. The structure of claim 1, wherein the moldedsubstrate is molded from resin of Polyphenylene Oxide.
 33. The structureof claim 1, wherein the molded substrate is molded from resin ofPolycyclo Terethalate.
 34. The structure of claim 1, wherein the moldedsubstrate is molded from resin of rigid rod Polyphenylene.
 35. Thestructure of claim 1, wherein the molded substrate is molded from resinof epoxies.
 36. The structure of claim 1, wherein the molded substrateis molded from resin of phenolics.
 37. The structure of claim 1, whereinthe molded substrate is molded from resin of thermoset Polyesters. 38.The structure of claim 1, wherein the molded substrate is molded fromresin of syndotactic Polystyrene.
 39. The structure of claim 1, whereinthe said electronic device is a leaded component.
 40. The structure ofclaim 1, wherein the electronic device is a surface mount component. 41.An electronic smart card comprising a chip assembled according toclaim
 1. 42. The structure of claim 1, wherein the said electronicdevice is surface mounted onto the printed traces and attached by curingthe Polymer Thick Film.
 43. The structure of claim 1 where the plasticsubstrate is formed by vacuum forming.
 44. The structure in claim 1where any portion of the circuitry is shielded with a conductive layer.45. The structure of claim 1 where a) a dielectric insulating layer isprinted over the circuit traces and attached electrical devices, and b)a shielding layer is printed over the dielectric insulating layer andconnected to a ground plane.
 46. The structure of claim 1, wherein saidelectronic device is a printed circuit board.
 47. The structure of claim1, wherein said electronic device is a silicon chip.
 48. An electronicpackage structure comprising: a molded substrate having first and secondopposing surfaces and a plurality of electronic devices disposed on atleast one of the said surfaces: said molded substrate having a pluralityof molded pockets on at least one of said opposing surfaces into whichsaid electronic devices are supported in said molded pockets, whereinsaid electronic devices are connected via a Polymer Thick Film ink tracebeing printed with a single print step on the surface of the said moldedsubstrate and the exposed termination pads of the electronic devicescontained in at least one of the molded pockets.
 49. An electronicpackage structure comprising: a molded substrate having first and secondopposing surfaces and a plurality of electronic devices disposed on atleast one of the said surfaces; said molded substrate having a pluralityof molded pockets on at least one of the said opposing surfaces intowhich said electronic devices are supported in said pockets, whereinsaid electronic devices are connected via a plurality of print steps ofPolymer Thick Film ink traces being printed on the surface of the saidmolded substrate and the exposed termination pads of the electronicdevices contained in at least one of the molded pockets.
 50. Thestructure of claim 48, wherein said electronic device is a silicon chipin the form of a bare die which is inserted into at least one of theplurality of molded pockets without first mounting the silicon chip in acarrier of any type.
 51. The structure of claim 48, wherein saidelectronic device is a chip in the form of a bare die which is insertedinto at least one of the molded pockets without first mounting the chipin a carrier of any type.
 52. The structure of claim 49, wherein saidelectronic device is a silicon chip in the form of a bare die which isinserted into at least one of the plurality of molded pockets withoutfirst mounting the silicon chip in a carrier of any type.
 53. Thestructure of claim 49, wherein said electronic device is a chip in theform of a bare die which is inserted into at least one of the moldedpockets without first mounting the chip in a carrier of any type. 54.The structure of claim 48 wherein a) a dielectric insulating layer isprinted over the circuit traces and attached electronic devices, and b)a shielding layer is printed over the dielectric layer and connected toa ground plane.
 55. The structure of claim 49, wherein a dielectriclayer is applied over the components supported in said pocket and overthe conductive traces.
 56. The structure of claim 49, wherein a) adielectric insulating layer is printed over the circuit traces andattached electronic devices, and b) a shielding layer is printed overthe dielectric layer and connected to a ground plane.
 57. The structureof claim 48, wherein a dielectric layer is applied over the componentssupported in said pocket and over the conductive traces.